Yolk-shell FeCu/NC electrocatalyst boosting high-performance zinc-air battery

Iron-nitrogen-carbon single-atom catalysts(Fe-N-C SACs)are widely acknowledged for their effective oxygen reduction activity,however,their activity requires further enhancement.Meanwhile,additional structural optimization is necessary to enhance mass transport and achieve higher power density in practical applications.Herein,using ZIF-8 as a template,we synthesized yolk-shell catalysts featuring complex sites of Fe single atoms and Cu nanoclusters(y-FeCu/NC)via partial etching and liquid-phase loading.The synthesized y-FeCu/NC catalyst exhibits high specific surface area and mesoporous volume.Combined with the advantages of highly active sites and yolk-shell structure,the y-FeCu/NC catalyst demonstrated outstanding catalytic performance in the oxygen reduction reaction,achieving a half-wave potential(E_(1/2))of 0.97 V in 0.1 M KOH.As a practical energy device,Zn-air battery(ZAB)assembled with y-FeCu/NC catalyst achieved a remarkable power density of 356.3 mW·cm^(-2),representing an improvement of approximately 28.5%compared to its solid FeCu/NC counterpart.Furthermore,it showcased impressive stability,surpassing all control samples.

Mesoporous Fe_(3)O_(4)@C nanoarrays as high-performance anode for rechargeable Ni/Fe battery

Rechargeable aqueous batteries with high power density and energy density are highly desired for electrochemical energy storage.Despite the recent reports of various cathode materials with ultrahigh pseudocapacitance exceeding3000 F g^(-1)(or 800 mA h g^(-1)),the development of anode materials is relatively insufficient,which limits the whole performance of the devices far from practical applications.Herein,we report the preparation of mesoporous Fe_(3)O_(4)@C nanoarrays as high-performance anode for rechargeable Ni/Fe battery by a self-generated sacrificial template method.Zn O/Fe_(3)O_(4)composite was first synthesized by a co-deposition process,and Zn O was subsequently removed by alkali etching to construct the mesoporous structure.A thin carbon film was introduced onto the surface of the electrode by the carbonization of glucose to increase the structural stability of the electrode.The unique mesoporous nanoarray architecture endows the electrode with larger specific surface area,faster charge/mass transport and higher utilization of Fe_(3)O_(4),which shows an ultrahigh specific capacity (292.4 mA h g^(-1)at a current density of 5 mA cm^(-2)) and superior stability in aqueous electrolyte (capacitance retention of 90.8%after 5000cycles).After assembled with hierarchical mesoporous Ni O nanoarray as a cathode,an optimized rechargeable Ni/Fe battery with double mesoporous nanoarray electrodes was fabricated,which provided high energy/power densities(213.3 W h kg^(-1)at 0.658 kW kg^(-1)and 20.7 kW kg^(-1)at113.9 W h kg^(-1),based on the total mass of the active materials)in the potential window of 1.5 V with excellent cyclability(81.7%retention after 5000 charge/discharge cycles).